1. Technical Field
This invention relates to air/smoke/fire dampers. In particular, it relates to dampers which can be controlled to be set and reset (i.e., closed and opened) locally or remotely under power, and which seal the damper under pressure when the damper blades are in the closed position, and which can modulate pressure levels to prevent smoke migration into designated non-smoking safety zones. It is also capable of setting normal operating building pressure differentials for cleaner air environments.
2. Background Art
Non-butterfly type dampers which can be closed automatically upon actuation by a heat-sensitive or other device are well-known in the art. Some such non-butterfly type dampers snap closed under either their own weight (i.e., gravity), or by mechanical force provided by springs.
As the art developed, external controls were devised to activate these dampers. Further, controls were also developed to cause the damper to be reset, that is, to be open in a ready position for heat responsive actuation in the event of fire or smoke conditions. A disadvantage of these prior art dampers is that they typically are activated by a separate device's exposure to the heat from a fire. As a result, they may disable the drive linkage making reactivation. Therefore, a substantial amount of smoke and even flames may pass through the damper before it is activated. It would be advantageous to have a damper system that could be activated well in advance of the fire or smoke to more effectively prevent either from passing through the damper.
An additional disadvantage associated with prior art systems is that these gravity or spring driven devices are slow to actuate. As a result, by the time the dampers are closed, substantial amounts of smoke, beat and even flames may have passed the damper and spread through the building.
In addition to problems caused by slow heat responsive closure, dampers which are then closed by gravity or spring driven devices do not always form an effective seal. As a result, even though the damper may be in the closed position, smoke and flames may penetrate the damper and spread to other parts of the building, causing property damage and personal injury. It would be desirable to have dampers that form an effective seal rather than merely temporarily contain either the fire or the progress of smoke, and to do so instantly, such that the potential damage from smoke, heat and flames is reduced.
While addressing the basic desirability of using dampers, the prior art has failed to provide a damper which can be powered closed well before advancing smoke and fire arrives, which creates an effective seal, and which can be sealed rapidly by a powered drive mechanism.